Ukraine has said it will file compensation claims with international courts over the annexation of Crimea, which Ukrainian Prime Minister Arseny Yatseniuk said could ultimately cost Kiev “hundreds of billions of dollars”.

Andriy Mokhnyk’s spokesman said the minister had told a news conference Ukraine intended to go to court to recover the money Ukraine would lose through its natural resources assets, which included businesses, 198 fields and 380 prospective ones.

“Ministry staff have assessed the market value of the resource base for Crimea. According to preliminary estimates, it was 127 billion hryvnias,” he told a news conference.

The region is home to offshore drilling firm Chernomorneftegaz (Chornomornaftohaz) and Russia has put Crimea’s oil reserves at 47 million tonnes and gas at 165.3 billion cubic metres, RIA news agency said.

Russia took over Crimea, home to Russia’s Black Sea Fleet, shortly after Ukrainian protesters toppled pro-Moscow President Viktor Yanukovich in February.

Moscow said it was protecting its compatriots there from nationalists from western Ukraine, but the country’s new leaders accuse Russia of waging a political campaign against them, using trade and the economy as weapons.